Question

newtons laws quiz
for each scenario in the chart, determine if the acceleration would increase, decrease or remain the same
a person is running with a heavy backpack and they drop the backpack and continue running.
a speed skater pushes backward with more force
a car continues at a constant velocity
during an iron man competition, a competitor has to lift heavier and heavier weights
2 people are pushing a broke down car into a parking lot, and one person gets lazy and stops pushing

Explanation:

Step1: Apply Newton's second law \(F = ma\) (where \(F\) is force, \(m\) is mass, \(a\) is acceleration)

For the first scenario: When the person drops the backpack, mass \(m\) decreases. Assuming the force applied (by the person's legs) remains the same (or changes minimally compared to the mass change), from \(a=\frac{F}{m}\), acceleration increases.

Step2: Analyze the second scenario

The speed - skater pushes with more force. Using \(a = \frac{F}{m}\) (assuming mass \(m\) of the skater and equipment is constant), as \(F\) increases, acceleration \(a\) increases.

Step3: Consider the third scenario

A car at constant velocity. By the definition of acceleration (\(a=\frac{\Delta v}{\Delta t}\)), if \(\Delta v = 0\) (constant velocity \(v\)), then \(a = 0\) (remains the same, specifically zero).

Step4: Examine the fourth scenario

In the iron - man competition, lifting heavier weights. Assuming the maximum force the competitor can apply is limited. Using \(a=\frac{F - mg}{m}\) (where \(F\) is the upward force, \(mg\) is the weight). As \(m\) (mass of the weight) increases, if \(F\) is approximately constant, \(a=\frac{F}{m}-g\) decreases.

Step5: Look at the fifth scenario

Two people pushing a car, one stops. The total force \(F\) applied to the car decreases. Assuming the mass \(m\) of the car is constant, from \(a=\frac{F}{m}\), acceleration decreases.

Answer:

1. Increase
2. Increase
3. Remain the same
4. Decrease
5. Decrease